The objective of this study is to develop a micturition assist device for the spinal cord injury patient with hyper-reflexic bladder paralysis. The device will be based on the technique of "collision block" of pudendal nerve activity for relaxation of the external urethral sphincter muscle and "sacral root stimulation" for activation of detrusor contraction. The focus of the study will be on research and development in animals of the collision block technique; sacral root stimulation techniques are under development elsewhere. The five phases of the study are concerned with: I the short-term development in animals of an effective method for eliciting relaxation of the external urethral sphincter and subsequent voiding using a pudendal nerve collision block; II the design and construction of an implantable electrode to induce the unidirectionally propagated action potentials required for collision block; III the development of a portable external stimulator to generate the collision block waveform; IV the development of a subsutaneous connector to permit percutaneous hardwiring the implant; and V the implantation and subsequent long-term evaluation of the efficacy and safety of the micturition assist device in animals. This research addresses a major health problem facing the majority of the estimated 200,000 spinal cord injury patients in the United States (to which 7,000 are added each year).